Wood finishing composition consisting of methylmethacrylate resin and borax



Unitet WOOD FINISHING COMPOSITION CONSISTING OF METHYLMETHACRYLATE RESINAND BORAX Jack Eastland, Atlanta, Ga., assignor to Eastland and Sapp,Atlanta, Ga., a partnership No Drawing. Application May 21, 1957 SerialNo. 660,478

7 Claims. (Cl. 117-72) This invention relates to protective andbeautifying wood finishes and more particularly to a process forfinishing wood and certain novel staining and sealing compositions usedin the process.

This application is a continuation-in-part of my eopending applicationfor patent Serial No. 549,565, filed November 28, 1955, now abandoned,which was in turn a continuation-in-part of my application for patentSerial No. 461,690, filed October 11, 1954, now abandoned.

It has heretofore been known that dark finishes for wood require the useof dark stains and fillers, which must penetrate the wood sufficientlyfar to permit of at least fine or finish sanding before or afterapplication of fillers, and before final protective finishes areapplied.

The most useful stains for achieving desired colors, particularly deepor intense colors on wood, are the penetrating water-soluble dyes orstains. These are water stains of great depth and resistance to fading.Their use is subject to a serious drawback in that the water which isthe solvent for these stains requires a relatively long drying period.Further, the use of water strongly raises the grain of the wood, whichthen requires further sanding. This generally involves the removal ofsubstantial amounts of the surface, together with added labor andmaterial costs as well as increasing the time required to complete thefinishing process.

To avoid the disadvantages of water-soluble dyes, the wood finishingindustry has heretofore commonly used as a practical commercial measureso-called non-grainraising stains. Such stains contain water-solubledyes dissolved in vehicles of the type of ethylene glycol, Carbitol andthe like. While they dry rapidly and do not raise the grain of the wood,these vehicles can dissolve only a limited amount of dye. Therefore,their use may require up to three or more applications to the surface tobe finished where a dark or strong color is to be achieved, because theyhave relatively much less intense staining properties. Furthermore, theresults produced by use of non-grain-raising stains are not as clear,brilliant and light-fast, nor as uniform, as with the formerly usedpenetrating water stains. A common practice when these stains are usedis to apply a wash coat of shellac or lacquer, which requires lightsanding. Thus, any advantage which the non-grain-raising stains may havehad over penetrating water stains by reason of their non-grain-raisingproperties is lost as a practical matter.

It is an object of this invention to provide a process for finishingwood in deep, strong colors which is rapid and which requires fewersteps than the formerly used production methods. Another object of thisinvention is to provide new sealing compositions for use in the saidprocess. A further object of the invention is to provide new staincompositions for use in the process of the invention which also havesealing properties. Other objects will be apparent from the disclosuremade hereinafter.

I have found that by employing as a vehicle or base for wood finishes anaqueous emulsion consisting of an 2,829,067 Patented Apr. 1, 1958acrylic resin dispersed in water together with certain sanding agents,to which can be added water-soluble dyes as well as other additives,compositions having both staining and sealing properties can be producedwhich make it possible to apply a superior finish to wooden surfaces ina relatively short time and with fewer operations than are normallyrequired.

Broadly speaking, the resin emulsion composition vehicle or base of myinvention comprises an aqueous acrylic emulsion together with a sandingagent, and to which can be added certain water-soluble dyes andviscosity and surface tension regulating agents. Additionally,lubricants, colored pigments, stabilizers and the like can be addedthereto if desired.

For the preparation of the novel compositions of my invention, which areconveniently termed dye-sealers because of their dual function when theycontain stains as compared with the stains of the prior art, I use amajor portion consisting of an aqueous emulsion of an acrylic resin anda minor portion consisting of a sanding agent, as f le borax, alone ortogether with Watersolubledy ji liihmsurface tension regulators. Thus, Ican employ an aqueous emulsion containing an acrylic resin such aspolymerized methyl methacrylate ranging in content from about 2% toabout 60% by weight of the final composition. Although the above rangeof compositions is operative, for convenience of formulation I prefer toemploy aqueous emulsions of polymerized methyl methacrylate ranging incontent from about 2% upwards to about 35% by weight of the finalsealing composition. For the above purposes any acrylic resin emulsioncan be used, such as an emulsion of a polymerization product of acrylicacid in water, or an aqueous emulsion of a polymerization product of anester of acrylic acid, as for example methyl acrylate or ethyl acrylate,or an aqueous emulsion of an ester of methacrylic acid, such as ethylmethacrylate, and the like. I prefer to employ polymerized methylmethacrylate, however, and a particularly convenient source of a methylmethacrylate resin emulsion is Rhoplex AC-33, a product manufactured bythe Rohm and Haas Company of Philadelphia, Pennsylvania which containsabout 45 of polymethyl methacrylate. I prefer to employ as an agent, toconfer sanding properties upon the vehicle after drying, borax or sodiumborate in amount of 0.074% to about 2.85% by weight. The maximum amountof this ingredient is actually governed solely by the quantity of waterpresent in the composition; for example sodium tetraborate on ananhydrous basis is soluble only to the extent of about 2% in water atordinary temperatures. Other water soluble sanding agents can of coursebe us ed in place of borax or sodium borate as will be apparent to thoseskilled in the art. As with borax and sodium borate, these sandingagents can be present up to the limit of their solubility in the acrylicresin emulsion. In practice, an upper limit for the sanding agent ofabout 2.85% by weight of the acrylic resin emulsion has been foundfeasible, although higher ranges are permissible.

The diluent of my compositions is water, and added thereto I can use anyof the water-soluble dyes or stains, of the type heretofore well knownto the art for their use in staining wood, in amounts ranging from 0.2%to the amount necessary to form a saturated solution in the basicemulsion vehicle which has as its ingredients polymethyl methacrylateemulsified in water and a watersoluble sanding agent such as borax. Inpractice, these water-soluble dyes or stains are present from about 0.2%to about 5% by weight of the basic emulsion vehicle.

Other additives and adjuvants can be used if desired, such asfungicides, say for example, boric acid, and the like, in eifectiveamounts ranging from about 0.25% to about 3%; thickcners for increasingviscosity, as for ex- 1.1%.! was): i1 angular ample, inorganicthickeners such as bentonite, montmorillonite, purified montmorillonitescomprising hydrous magnesium silicate and the like, and organicthickeners such as methyl cellulose, ethyl cellulose, carboxymethylcellulose, hydroxyethyl cellulose, and the like; wetting agents, such assodium lauryl sulfosuccinate, and the like; hiding pigments, such astitanium dioxide, iron oxide, lamp black and the like; water-soluble orwater-emulsifiable waxes, such as the synthetic and natural waxesexemplified by carbowax and carnauba wax, respectively, and the like;and surface-tension reducing agents, such as ethylene glycol, diethleneglycol and the like.

I have found that it is very useful to add a sufiicient amount of athickening agent, such as hydroxyethyl cellulose or hydrous magnesiumsilicate to increase the viscosity of the dye-sealer compositionaccording to the mode of application and the surface to which they areapplied, to a point where no sagging will occur. However, whenthickeners are added, they also increase the surface tension of thedye-sealer, and when used in amounts of 1.5% or more they preventpenetration of the pores or open grain of the wood. This produces noveleffects where desired. However, I have found that the addition of acertain amount of a water-soluble glycol such as ethylene glycol,diethylene glycol and the like reduces the surface tension to a pointwhere the dyesealer fills the pores or open grain of the wood, withoutsubstantial effect on the viscosity and prevention of sagging. Theamount of soluble glycol which I employ ranges from that amount justefiective to reduce the surface tension up to about 4% by weight of theamount of resin solids in the emulsion. Thus, by the use of the saidthickening agents, combined with surface-tension lowering agents, theextent to which the pores of the wood absorb the dye-seal by capillaryattraction can be definitely and reproducibly controlled.

Particularly advantageous wood sealing compositions are those containingin addition to the basic emulsion vehicle, a hydrous magnesium silicatethickener present from about 0.2% to about 1% by weight of the finalcomposition. This hydrous magnesium silicate is a highly purifiedmagnesium montmorillonite containing on a dry basis about 56% silica,about 26% magnesia, and lesser amounts of calcium oxide, ferric oxide,alumina, and alkali metals. A suitable variety of a hydrous magnesiumsilicate is Ben-A-Gel, a product of the National Lead Company. Theparticular advantage of wood finishing compositions containing hydrousmagnesium silicate as a thickener is the virtual elimination of lappingwhen applied to a surface and the increased ability of the emulsionpresent in the final wood finishing composition giving it a longshelf-life.

When the novel dye-seal compositions made in accordance with the abovedescription are used for finishing wooden surfaces, I have found thatgreat uniformity of color is produced even in dissimilar woods.Generally, no shading is necessary with my new compositions, whereaswith conventional stains this procedure is always required in greater orless degree in production work. This elimination of shading or reductionin the 'amount of shading required results in a large decrease in costof production, because shading is largely a manual operation. Thus, useof the dye-seal compositions of this invention is economical of bothtime and materials as well as yielding superior results.

Surprisingly, even though the vehicle of my novel dyeseal is Water, thegrain of the wood to which it is applied is raised only slightly, sothat only a minimum amount of fine or light sanding is necessary. Thus,no more sanding is required than that which would be necessary followinga wash coat. Furthermorme, the final finish when applied is invariablyof much greater clarity, more resilience and much greater resistance toimpact than the same final finish, be it one or more lacquer or varnishcoats, applied over conventional stains and separate sealers. Thefinishes produced using my acrylic emulsion based dye-sealers are alsomuch more coldcheck resistant than conventional finishes.

An important advantage of the use of my novel sealing and dyeingcompositions in Wood finishing accrues from the substantial eliminationof open grain and pin holes on the finished surfaces. This condition,which commonly is caused by film failure or the like during sealingoperations, is almost impossible to detect in normal manufacturingprocedures until after the finished article has gone through the rubbingprocess. By eliminating this cause for rejection of finished pieces, andthe expensive re-working which is required to salvage such rejects, thenew sealing composition brings about important savings in the costs offinishing wooden surfaces.

The compositions of my invention are employed for wood finishing asfollows:

A wooden surface which has been smooth-sanded to any desired degree isstained to the color desired by brushing, spraying or Wiping over thesurface one application of a dye-sealer of the type described in thefore going disclosure. Previous glue-sizing of the wood is notnecessary. The stained, sealed surface is permitted to dry thoroughly inair at room temperature, which requires only about fifteen to thirtyminutes, depending on the humidity and other factors such as percentageof water present in the dye-seal.

The stained and/ or sealed surface is then sanded lightly to remove thevery slightly raised grain.

The surface can now be finished with clear varnish or lacquer, if afiller is not required with the wood surface to be finished, e. g.,gumwood.

If the nature of the surface requires a filler, any filler compositionof the type known to the art is next applied by brushing, wiping orspraying, as desired. Any excess of filler which may be present is wipedoff, and the filled surface is dried, at room temperature or with theuse of heat as desired.

The surface is now ready for final varnish or lacquer finish coats. Insome instances additional sealing coats will be required, but these willbe reduced in number compared with the same article finished byconventional means. Any desired depth of color can be obtained in onlyone application of the dye-sealer composition of this invention.

The following examples will illustrate specific embodiments of thedye-seal compositions of my invention.

Example 1.Basic emulsion vehicle range of 2.85%.

Conveniently, the methylmethacrylate resin is used in the form of anaqueous emulsion containing about 45% solids, thus furnishing a portionof the water used. The borax and the remainder of the water are added tothe aqueous emulsion, and the mixture is thoroughly agitated until it ishomogeneous. It is then ready for use. To the basic vehicle thusprepared can be added:

Lbs. Permissible range Water-soluble dye (in sufficient 2 About 0.1% tolimit of amount). solubility in basic emulsion vehicle (about 6%).

Additionally there can be added agents which thicken or provide body toprevent sagging and/or raise surface tension where distinct porecharacteristics are desired such as opaque finishes on walnut andmahogany, preservatives, surface-tension reducing agents, hidingpigments and the like, depending on the application to be made, asdescribed hereinabove.

Example 2.-Preparation of dye-seal, transparent mahogany color Thefollowing amounts of ingredients are used:

Permissible Lbs. range,

percent Water 200 37 to 97.8. Aqueous rnethylmethacrylate resin emulsion185 2 to 60.

containing 83.25 pounds of methylmethacrylate resin and 101.75 pounds ofwater, (Rohm and Haas AC 33, 45% solids). Borax, finely powdered 7 0.074to 2.85. Diethylene glycol 4 to 4. oric acid 2 0 to 2.Hydroxyethylcellulose, 2% in water 60 0 to l. Antifoam agent, Nopco1497V (a modified amido 1 0 to 0.5.

condensation product obtainable from the Nopco Chemical 00., Harrison,N. J.). Orange Y (ealcocid) 2 0 to 5 Brilliant Red B 2% 0 to 5 lue-black14 0 to 5 To the water are added successively, with continuousagitation, the borax, boric acid, diethylene glycol, antifoam agent, thedyes, hydroxyethylcellulose and the resin emulsion.

60 lbs. of a 3% suspension of a hydrous magnesium silicate in water canbe used in place of the hydroxyethyl cellulose in the above composition.

After all of the acrylic emulsion has been added, the mixture isstrained through a cloth or screen of about 32 mesh, and is then placedin suitable containers and is ready for use.

Example 3.--Preparati0n of opaque dye-seal, grey colored The followingingredients are used.

Parts Permissible by Range, Weight Percent Water 16 37 to 97 8Methylmethaerylate aqueous 45% emulsion 120 2 to 60.

containing 54 lbs. of methylmethacrylate r eiinseasnd 66 lbs. of water,(Rohm and Haas Borax 5 0.074 to 2.85 Boric Acid 1. 5 0 to 2.Hydroxyethyl cellulose, 2% in water 45 0 to 1. Titanium Dioxide, finelyground 1. 5 0 to 30. Mapico black 0. 5 0 to 20. Antifoam agent (Nopco1497V) 0. 3 0 to 0.5. Tamol 731 (Sodium salt of a carboxylated 0. 3 0 to0.5.

galyelectrolyte obtainable from Rohm & aast 00., Philadelphia,Pa.)-Dispersing agen The mixture is prepared as in Example 1 except thatthe titanium dioxide and Mapico black are ground with part of the waterand are added last of all, with thorough stirring.

45 lbs. of a 3% water suspension of a hydrous magnesium silicate can beused in place of hydroxyethyl cellulose in the above composition.

Example 4.-Comp0sition for under-coating and the like To a basicemulsion vehicle, prepared as in Example 1, is added about 100 pounds ofa 3% suspension of hydrous magnesium silicate in water. The finalunder-coating composition thus prepared has the following composition:

23.8% polymethyl methacrylate 1.9% borax 0.8% hydrous magnesium silicate73.5% water Example 5.Preparation of dye seal, basic The followingamounts of ingredients are used:

The amount of dye used in the above composition is exemplary only, andthe actual amount used will depend upon the strength of the dye, thedepth of color desired and the solubility of the dye in the basicemulsion vehicle containing added ingredients, as above.

In preparing a dye seal of the above composition, the hydrous magnesiumsilicate and 1.5 lbs. of boric acid are ground in a pebble mill overnight, with lb. of water. The resulting suspension, the borax, theremainder of the boric acid, the dye, the antifoam agent, the diethyleneglycol and about 75 lbs. of water are placed in a mixing tank and mixedat high speed for about 15 minutes. The balance of the Water (75 lbs.)is then added and mixing is continued for ten more minutes. The mixingrate is cut to about half and the 45% polymethyl methacrylate emulsionis added steadily but gradually. After the addition is complete, mixingis continued one more minute and the resultant composition is strainedthrough four thicknesses of cheesecloth into shipping containers.

The invention claimed is:

1. A wood finishing composition having as a major ingredient a basicemulsion vehicle containing about 2 to 60% by weight of arnethylmethacrylate resin, about 0.074 to 2.85% by weight of borax andwater to 100%, said rnethylmethacrylate resin being emulsified in thesaid water.

2. A wood finishing composition comprising a basic emulsion vehiclecontaining from about 2 to 60% by weight of a methyl methacrylate resin,about 0.074 to 2.85% by weight of borax, water to 100%, and as an addedingredient a water-soluble dye ranging in amout from that necessary togive a 0.2% solution to that necessary to give a saturated solution inthe said basic emulsion vehicle.

3. A wood finishing composition comprising a basic emulsion vehiclecontaining from about 2 to 60% by weight of a methyl methacrylate resin,about 0.074 to 2.85% by weight of borax, water to 100%, and as an addedingredient a thickening agent in a concentration not to exceed 1% byweight of the final composition.

4. A wood finishing composition comprising, in combination, a basicemulsion vehicle about '2 to 35% by weight of a methyl methacrylateresinfabout 0.12 to 2.85% by weight of borax and water to 100%, saidmethyl methacrylate resin being emulsified in water, and as an addedingredient a water-soluble dye ranging in amount from that necessary togive a 0.2% solution by weight in the basic emulsion vehicle to thatnecessary to give a saturated solution of the dye in the said basicemulsion vehicle.

5. A wood finishing composition comprising, in combination, from about 2to 35% by weight of a methyl methacrylate resin, from about 0.12 to2.85% by weight of borax, from about 0.2 to 1% by weight of a thick- 7ening agent, and a water-soluble glycol not to exceed 4% by weight andwater to 100%, said methyl methacrylate resin being emulsified in saidwater.

6. The process of finishing wood surfaces, the step which comprisesapplying to said surface a composition comprising an aqueous emulsion ofa methyl methacrylate resin containing about 35% by weight of resin andfrom 0.2 to 2.85% by weight of borax, and thereafter j drying.

7. The process of claim 6 in which a substantially No references cited.

6. THE PROCESS OF FINISHING WOOD SURFACES, THE STEP WHICH COMPRISESAPPLYING TO SAID SURFACE A COMPOSITION COMPRISING AN AQUEOUS EMULSION OFA METHYL METHACRYLATE RESIN CONTAINING ABOUT 35% BY WEIGHT OF RESIN ANDFROM 0.2 TO 2.85% BY WEIGHT OF BORAX, AND THERAFTER DRYING.
 7. THEPROCESS OF CLAIM 6 IN WHICH A SUBSTANTIALLY TRANSPARENT FINISH COATINGIS SUBSEQUENTLY APPLIED TO THE DRIED METHYLMETHACRYLATE COATING.